Evidence has linked many diseases such as heart disease and lung cancer to cigarette smoking. Each year, many deaths are caused by cigarette-related diseases. Indeed, excessive smoking is recognized as one of the major health problems throughout the world.
One reason it is extremely difficult for a smoker to quit is the addictive nature of nicotine. Even though nicotine is one of the risk factors in tobacco smoke, other substances formed during the combustion of tobacco, such as carbon monoxide, tar products, aldehydes and hydrocyanic acid, are considered by many to be a greater risk to the health of smokers.
In order to help smokers reduce or stop smoking altogether, acceptable alternatives have been provided to deliver nicotine in a form or manner other than by smoking. A number of products have been developed to accomplish this result. The first successful product used as a smoking substitute and/or smoking cessation aid was a chewing gum known as Nicorette.RTM. which contains nicotine as one of its active ingredients. See U.S. Pat. Nos. 3,877,486; 3,901,248; and 3,845,217.
Another product which has recently been marketed is a transdermal patch which includes a reservoir that holds nicotine base, as well as other drugs. When nicotine is transmitted through the skin into the user's bloodstream, it tends to alleviate a smoker's craving for nicotine. See U.S. Pat. Nos. 4,915,950 and 4,597,961. Nicotine nasal sprays have also been developed, both for use with a patch and independently. See U.S. Pat. Nos. 4,579,858 and 4,953,572.
All of these products have demonstrated some degree of success to the principles of nicotine replacement as an aid to smoking cessation, and that nicotine replacement can facilitate smoking cessation by providing some relief for certain withdrawal symptoms such as irritability and difficulty in concentrating. However, there still remains the subjective craving for cigarettes that is not effectively relieved by the pharmacologic effects of nicotine alone.
Some authorities have concluded that the sensations experienced in the upper and lower respiratory tracts, including the oral cavity upon inhalation of each puff of cigarette smoke, along with the taste and aroma of the smoke and the act of puffing, provide a considerable portion of the satisfaction experienced by a smoker. These sensory cues, in addition to the chemical dependency, are believed to help maintain a dependency on cigarettes which previously marketed products are unable to satisfy. Therefore, there is a need to develop smoking cessation aids which deliver the sensory and habitual aspects of smoking, in addition to the other substances found in cigarette smoke.
Many smoking cessation products have been developed, which simulate or closely approximate the look, feel, and taste of cigarettes for orally administering nicotine to the user. For example, attempts have been made to develop a smokeless cigarette where a heating element is used in combination with various types of carriers impregnated with nicotine base or nicotine in other forms. See, for example, U.S. Pat. Nos. 4,848,374; 4,892,109; 4,969,476; and 5,080,115.
Other attempts have been made to provide inhalers where nicotine base is stored in a reservoir mounted in a tubular housing, and aerosol droplets in an airstream or combined with a propellant are delivered orally. See, for example, U.S. Pat. Nos. 2,860,638; 4,284,089, 4,800,903 and 4,736,775.
These products have encountered various problems such as, for example, difficulty in providing a satisfactory shelf life, an inability to deliver sufficient amounts of nicotine directly into the lungs of the user and an unpleasant taste.
In addition to transmitting various nicotine compounds transdermally, nasally and orally, it has also been found that an aerosol in the form of a spray containing measured amounts of a food acid such as citric acid can be used to stem the craving for nicotine. Citric acid particles have been combined with a liquid carrier and administered alone or together with nicotine transdermally or with small amounts of tobacco smoke, to help in a smoking cessation program. See U.S. Pat. No. 4,715,387.
Attention has also been directed to delivering nicotine and other therapeutic compounds through the mouth in the form of a dry powder. It has been reported that in order to deliver a powder directly into the lower respiratory regions the powder should have a particle size of less than 5.mu.. Further, powders in the 5-10.mu. range have been found not to penetrate as deeply and instead tend to stimulate the higher respiratory tract regions. See U.S. Pat. No. 4,635,651.
Because particles of these small sizes tend to agglomerate or form lumps, especially when exposed to moisture, the powders must be maintained in a dry state or the lumps broken up before they are delivered. Several devices have been developed where the powder is maintained in a capsule which has to be broken or punctured before the powder is delivered. See, for example, U.S. Pat. Nos. 3,858,582; 3,888,253; 3,991,762; 3,973,566; 4,338,931; and 5,070,870. These devices tend to be bulky or expensive to manufacture because they must provide a mechanism for breaking the capsule and metering the amount of powder to be delivered.
Other devices have been developed where dry powder is maintained in a chamber and metered doses are administered by rotating or moving various parts (U.S. Pat. No. 4,570,630; EPO 0 407 028 A2; GB 2,041,763; PCT WO 91/02558), or dry powder is carried in a web of material and the powder is removed by impact, brushing, or air current (PCT WO 90/13327; WO 92/00115). These devices all involve relatively complicated mechanical structures that are expensive to manufacture and cannot be incorporated into an elongated tubular holder.
Several other devices have been suggested where a single dose of powder is packaged in a container, but there is no provision for a multi-dose application or prevention of particle agglomeration. See, for example, U.S. Pat. No. 4,265,236; EPO 0 404 454.
Most of the dry powder devices are designed primarily to deliver measured amounts of powder directly into the lungs by providing a very low pressure drop across the chamber in which the powder is charged. While this action is satisfactory for asthma and other congestive ailments, it is much different from that of a smoker where a cloud of particles is drawn first into the mouth and then into the lungs. The action of a cigarette is more closely approximated by a much greater pressure drop in the inhaler device.
Thus, there is a need for an elongated container which can be used to deliver properly-sized dry particles of a therapeutic compound which prevents the particles from agglomerating, is relatively inexpensive to manufacture with a minimal number of components, and can closely approximate the drawing action of a smoker.